The intake manifold fitted to the modern automotive vehicle delivers incoming air from the air filter into the combustion chamber. Components associated with the intake manifold include the throttle body, the mass air flow sensor, various ducts and a fuel rail. The conventional intake manifold includes a plenum and an intake runner formed between the plenum and each cylinder.
The volume of the plenum and the geometry of the individual runner dictate engine performance. In the typical engine, the runner geometry is fixed. Engine performance may be modified by changing the volume of the plenum and the geometry of the runner. However, the fixed volume of the plenum and the fixed geometry of the runner, even when tuned for a specific engine and desired performance characteristics, are not perfectly suited for every engine speed. The most desirable aspect to adjust over different engine speeds is the length of the runner.
In an effort to improve engine performance, an active air intake manifold was developed which includes a valve to regulate the incoming air/fuel mix. An open valve forms a longer path for the incoming air/fuel mix, a condition that is desirable when the engine is operating at low revolutions. On the other hand, a closed valve shortens the runner path to improve engine performance when operating at high revolutions.
Another approach to improving engine performance is through the provision of a charge motion control valve (CMCV) system in which a flap is movably fitted in the primary runner. According to this system, the movable flap may partially and selectively block the air flow. By so doing, turbulence is created that helps improve fuel mixing at lower engine speeds.
In today's vehicle, the vacuum solenoid has several rubber hoses that connect it to the other parts of the intake system, including a vacuum hose to the intake manifold vacuum reservoir. These hoses take up space in the vehicle's engine compartment and add weight to the vehicle. The hoses also add material cost to the vehicle and require labor for their installation. Furthermore, experience has shown that rubber hoses introduce into the system an opportunity for leakage, thus causing vehicle performance problems. The problems associated with leaking hoses become more pronounced as the vehicle ages.
Thus known approaches to attaching the vacuum solenoid to the intake manifold reservoir are undesirable and impractical. Accordingly, an improved arrangement for associating the vacuum solenoid with the intake manifold remains wanting.